Cerumen or earwax is composed of desquamated sheets of corneocytes originating from the deep and superficial external auditory canal, mixed with glandular secretions. These glandular secretions originate in the sebaceous and ceruminous glands in the auditory canal secrete lipids and peptides, respectively, into the cerumen. Hairs in the external third of the canal also produce glandular secretions that contribute to cerumen's composition. Cerumen forms a protective layer on the skin of the external ear canal. The consistency of, and thus the difficulty in removing, cerumen varies from individual to individual and is at least partially genetically determined.
Cerumen build-up and impaction in the external ear canal is a significant problem, especially for the infant and geriatric populations of the world. In the United States, about 8 million cerumen removals take place each year, and in the United Kingdom, the number is 2 million. Individuals possessing hairy ear canals, narrow ear canals, or osteoma are more disposed to such build-up or impaction. In addition, some literature suggests that the use of cotton buds to clean the external ear canal interferes with the body's normal shedding of earwax and epithelium and increases the chance of such build-up and impaction. Build-up and/or impaction of earwax may cause irritation, itching, pain, infection, or conductive hearing loss. Wax removal is necessary to alleviate these conditions. Cerumen removal is also required when it is necessary to examine the tympanic membrane. The process of removing impacted cerumen is tedious and time consuming for health care providers and is often painful for the patient.
Various compositions for allegedly softening or removing human cerumen are known. Several commercial products contain carbamide peroxide (6.5%) in an anhydrous glycerin vehicle as defined in the FDA monograph 21 CFR part 344. Examples of these products are Debrox® Earwax Removal Aid, Murine® Ear Wax Removal Drops, and Flents® Earwax Removal Aid. Another product is Cerumenex® Eardrops, a prescription product containing triethanolamine polypeptide oleate-condensate (10%). Cerumenex® sometimes resulted in irritation of the ear canal, and its distribution was discontinued in 2002 in the United States.
In addition, other agents have been somewhat effective in softening earwax. Such agents include glycerin (glycerol), olive oil, almond oil, mineral oil, sodium carbonate, sodium bicarbonate, hydrogen peroxide, docusate sodium, and dichlorobenzene. After softening with one of these agents, irrigation with body temperature water or saline is often performed to remove the softened cerumen. However, there is literature that reports that Cerumenex® Eardrops and Murine® Ear Drops were no more effective that placebo (saline) in a randomized, controlled clinical evaluation.
Compositions that may facilitate the removal of earwax have also been the subject of several patents and patent applications. For example, U.S. Pat. No. 4,895,875 (Winston) discloses stabilized peroxide solutions comprising urea peroxide and glycerin and methods of preparation and uses for cerumen removal; U.S. Pat. No. 5,296,472 (Sanchez et al.) discloses compositions comprising cyclodextrins and methods of use for cerumen removal; and U.S. Pat. No. 5,480,658 (Melman) discloses compositions comprising acetic acid and boric acid in a water base useful for cleaning the external ear canal of pets. Patent application US2004/0126436 (Cagle et al.) proposes a cerumenolytic composition utilizing a methyl trypsin protease enzyme to assist in the removal of human cerumen from the external ear canal. And patent application WO2011085155A2 (Shapiro et al.) describes a product consisting of bile salts, limonene, and sodium bicarbonate for the dissolution and removal of human cerumen.
Yet another cerumenolytic product is an aqueous solution of sodium bicarbonate, which has been prepared by physicians and used to treat impacted cerumen. If this solution is used, physicians are inconvenienced by having to prepare the solution for each individual patient.